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Old 07-22-2014, 09:11 PM
FrankGRUN FrankGRUN is online now
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Carb Jetting with Dual Fuel Setup

I'm finally about to finish restoring my 1982 E350-based Dual Fuel Motorhome. I had to replace the stock motor with a remanufactured 460 long block. The replacement was built with a Melling MTF-3 RV cam, and the cam timing has been set to 2 degrees advanced from the 8 degrees retard factory setting. I'm using an Edelbrock 1411 750 cfm carb with an Edelbrock Performer 2166 manifold. The smog hardware is disabled (EGR and air pump) and the exhaust system consists of Headman Elite Long Pipe ceramic coated headers feeding a 3" single exhaust through a very large high flow muffler. The right and left side exhaust pipes from the headers meet about halfway from the right side exhaust manifold to the inlet to the muffler. Duals were not possible because of interference with the motorhome holding tanks. The ignition system uses the Ford Duraspark II distributor, recurved for RV applications, and a Crane Hi-6s ignition multispark system. The plugs are Autolite XP-25. The transmission is a C6 automatic with RV torque converter and a Gear Vendors Overdrive. In overdrive I'm turning 2300 rpm at 55 mph. The motorhome is 24 ft. long, weighs 11,000 pounds and resembles a large barn door moving down the highway.

When I added the headers, the airflow in the stock engine increased to the point that the 1411 was running rich and I had to rejet to 1 stage leaner main jet and metering rod.

Now as I convert to dual fuel, I will be bolting an IMPCO 425 to a right angle adapter to the top of the 1411. I will use an IMPCO Model E converter and a Dual Curve Timing adapter as well as the IMPCO Commander Controller for the 425. Another right angle adapter will be used to connect to the high flow in-line air cleaner.

My question is this: With the right angle connection to the IMPCO 425 and the air flow restrictions intrinsic to the 425 mixer, will this impede the air flow seen by the Edelbrock 1411 to such an extent that the 1411 has to be rejected?

Any help would be greatly appreciated.

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